Showing papers on "Contact area published in 1990"

Isotropic Constitutive Model for Sintering Particle Packings

Abstract: This paper presents an isotropic model for the effective viscosities of sintering particle packings. The relationship between the macroscopic stress and deformation rate is based on the behavior of individual interparticle contacts, represented by contact viscosities, and the statistics of the packing. The contact viscosities depend on the contact area, which is the primary variable used to describe the state of the packing. A direct consequence of this choice of state variable is that the effective viscosities are identically zero for an undeformed and unsintered packing. Specific results are presented for the case of Newtonian viscous materials. The model is compared with existing models for porous Newtonian viscous materials. Experiments conducted with spherical glass powder packings show good agreement with the model. Finite-element simulations using the model have been used to study forging of a pellet.

Capacitive pressure sensor

Abstract: A capacitive pressure sensor includes a set of facing electrodes arranged with a cavity disposed therebetween and having insulation layers respectively formed on the surfaces thereof. The contact area between the facing electrodes varies directly with the applied pressure, and variation in the contact area causes variation in the capacitance which is detected as a pressure measurement. Since the capacitance variation is proportional to the applied pressure, a pressure signal which is substantially linear can be obtained. Therefore, the capacitive pressure sensor of this invention can measure pressure with high precision.

A Numerical Model of the Load Transmission in the Tibio-Femoral Contact Area

Abstract: An axisymmetric finite element model is applied to the analysis of the force transmission between the tibia-meniscus-femur. The model assumes linear elastic material properties, static loading and sliding contact between the components. The study explores the effects of (a) tibial surface geometry (plane, convex, concave), (b) inclusion of soft layers on the bony components and (c) anisotropic properties of the meniscus. When soft layers are absent, tibial surface geometry is found to affect the total axial stiffness of the model, the radial displacement of the meniscal ring as well as the meniscal share in load transmission. Inclusion of soft layers yields qualitatively the same results for the different geometries, under the understanding that axial stiffness decreases while meniscal radial displacements increase. However, the effect of tibial geometry on the meniscal share in load transmission almost disappears as soon as soft layers are applied, while at the same time a significant increase of this share is observed. Increased circumferential stiffness of the meniscal ring raises this share even more.

Electrical contacts for an electro-optic modulator

Abstract: A contact structure and method of formation of a contact structure for an electro-optic modulator. Linear electrodes on a modulator crystal are covered with a dielectric layer. The electrodes are contacted by way of one or more vias through the dielectric layer. Contact pads are formed over the vias so as to contact the electrode and extend over several adjacent electrodes, providing significantly greater contact area for a driver chip applied to the modulator crystal.

Time-wise increases in contact resistance due to surface roughness and corrosion

Abstract: To understand failure and estimate connector reliability a connector model was made in which two mated rough copper surfaces were subjected to ingression and corrosive attack by atmospheric oxygen. The rough surface segments the connector contact area into many small discrete areas (a-spots) through which currents flow. The initial a-spot contact radii a/sub e/ (formed as metal-to-metal bridges by mating surface heights on the mating surfaces) was determined by the externally applied load, connector materials, geometry, and surface topography. Later, corrosive attack of the metallic surfaces cause the metallic contact radii to shrink and resistances to increase. Factors in the model that influence the corrosive process are environmental temperature, partial pressure of oxygen, and geometric factors associated with the contact. Resulting curves of contact resistance versus time are similar in trend and shape to experimentally measured curves by Takano and Mano. From time variations of contact resistance of the connector, methods for estimating the useful lifetime of electrical connectors are given. >

Apparatus and method for observing the ground contact patch of a tyre

Abstract: An apparatus and method in which light from source is kept within a transparent moving roadway and a tire tread is pressed onto one surface of the roadway The ground contact patch of the tire is observed from the opposite side, and the ground contact area and the non-ground contact area of the tire tread is distinguished clearly The dynamic behaviour of the ground contact patch of the rotating tire roadway can be observed by means of a camera unit The information obtained can be utilized for tire design to improve tire performance

Relationship between tire deflection characteristics and 2-d tire contact area

Abstract: We have developed mathematical expressions for 2-D contact length, contact width, and contact area of a pneumatic tire on a rigid surface based on the geometry and deflection characteristics of the tire. These expressions show that the 2-D contact area is elliptical when the tire deflection is small but becomes rectangular with curved edges as the deflection increases. The model predictions were verified using experimental results obtained using 16.9R38, 18.4R38, and 24.5R32 tires. Simulation studies were conducted to predict the effects of tire load, inflation pressure, and geometry on contact traces.

Photoelectric conversion device

Abstract: PURPOSE:To reduce electrode occupation ration of a light-receiving surface, reduce series resistance, and improve efficiency by forming a semiconductor diffusion layer of conductivity type which is different from that of a semiconductor substrate formed on the surface of the semiconductor substrate containing a mechanical machining groove and an electrode embedded into the groove. CONSTITUTION:Before forming a diffusion layer of a light-receiving surface, a groove 10 of a desired shape is provided on the surface at the light-receiving side of a semiconductor substrate 1, a diffusion layer 2 is provided on the entire surface including this groove 10, and an electrode 6 is provided on the surface of the diffusion layer 2 including this groove 10, and an electrode 6 is provided on the surface of the diffusion layer 2 at the part of the groove 10. It reduces the occupied area of the electrode on the light-receiving surface but increases the contact area with the diffusion layer on the light-receiving surface., thus reducing contact resistance as well as series resistance and improving collection efficiency of current generated by light as well as a curve factor. Also, by forming a groove by mechanical machining and allowing machining distortion generated on machining to remain as it is, it becomes possible to deepen the junction depth only at the periphery of the electrode provided at the groove and to reduce contact resistance by utilizing high-speed diffusion of impurities at this residual distorted part.

Improved contact metallization for high efficiency EFG polycrystalline silicon solar cells

Abstract: Improvements in the performance of polycrystalline silicon solar cells based on a novel, laser-patterned contact process are described. Small lots of cells having an average conversion efficiency of 14+%, with several cells approaching 15%, are reported for cells of 45 cm/sup 2/ area. The high-efficiency contact design is based on YAG laser patterning of the silicon nitride antireflection (AR) coating. The Cu metallization is done using light-induced plating, with the cell providing the driving voltage for the plating process. The Cu electrodeposits into the laser-defined windows in the AR coating for reduced contact area, after which it bridges on top of the Ar coating to form a continuous finger pattern. The higher cell conversion efficiency is attributed to reduced shadow loss, higher junction quality, and reduced metal-semiconductor interfacial area. >

Two‐Dimensional Contact Pressure Distribution of a Radial Tire

Abstract: Two‐dimensional contact pressure distribution of a radial tire, statically compressed to a flat roadway, is analyzed using a rectangular contact patch. The tire structure is modeled by a spring‐bedded ring belt comprised of a laminated‐biased composite strip. The belt is supported by radial springs simulating the sidewall. The spring constant Kr was well defined previously by one of the authors. Deformation of the rectangular flat belt is obtained theoretically. The belt is subjected to inflation pressure, reaction forces transmitted from the spring bed of the tread rubber, and shearing force and bending moment along the belt boundaries brought from side‐wall springs and the detached part of the ring belt. In‐plane membrane forces, which are not uniform in the contact area, due to the friction forces acting between the tread surface and the roadway are also applied. The resulting contact pressure distributions in the circumferential direction are shown to be convex along the shoulder, but concave...

Hydraulic seal assembly

Abstract: An improved seal for use in a hydraulic system such as a piston rod in a housing, the seal having a stressing member and sealing member in which the latter is in point contact with, for example, a piston rod under low fluid pressure and has an additional contact area with the piston rod under high fluid pressure; a shallow concavity between the point contact and the contact area entraps lubricating fluid when the seal is subjected to high fluid pressure. In another modification the sealing member has an incline on the face in contact with the stressing member so that under high fluid pressure, the stressing member is forced up the incline and thus exerts increased pressure through the sealing member against the contact area and produces an effective high fluid pressure seal. In still another embodiment the sealing member has a concave surface to receive the stressing member such that it is centered, during low pressure operation, over a sealing contact area of the sealing member.

Determination of contact area in 'cushion form' bearings for artificial hip joints.

Abstract: Current forms of artificial hip joints produce wear debris, which contributes to loosening of the prostheses. These 'hard' joints articulate with boundary or mixed lubrication, whereas the natural joint articulates with full fluid film lubrication. An artificial joint that articulates with full fluid film lubrication could greatly reduce wear and frictional torque and hence reduce the incidence of loosening and inflammatory tissue reaction. The use of a thin lining of low elastic modulus in the acetabular cup is one possible way of promoting full fluid film lubrication. In the design of such cushion forms of bearings, it is important to be able to predict the contact area, stress distribution and film thickness. This paper presents experimental techniques to determine the contact area in low elastic modulus layers and compares these measured areas with theoretical predictions using linear elasticity theory. At low loads experimental results and theoretical predictions were close. However, at loads above 300 N, the theory overestimated the width of the contact area by up to 8.5 per cent. This difference is mainly attributed to the non-linear behaviour of the elastomer at the higher levels of stress.

Deflectable contact for providing positive surface contact for shielding electromagnetic interference

Abstract: There is disclosed an electromagnetic compatibility grounding connector having a contact portion deflectable between a first and a second position. In the first position only a line contact is established in contact with a complementary connector. In a second position a surface contact is established of greater surface contact area than the line contact. Electrical resistance is thus reduced and conductivity increased. Also disclosed is a support for an electronic device having such a connector and a personal computer housing having such supports and interconnecting with such connectors.

Low-resistance noble metal contacts to high-temperature superconductors

Abstract: Low-resistance contacts were made to both YBa2Cu3O(7-x) and Bi2BaSr2Cu2O8, and to related superconducting compounds by melting gold or silver pads onto the samples before the final oxygen treatment. Scanning electron microscope studies show that both gold and silver do not diffuse far from the contact area. The surface contact resistivity of the best contacts made by the melting technique has an upper limit value in the 10 to the -8th ohm sq cm range at 77 K. This contact resistivity shows no significant change in its value over a period of 17 months. Furthermore, an electron radiation dose of 5.7 x 10 to the 17th electron/sq cm only doubled the contact resistivity.

Semiconductor device and its production

Abstract: PURPOSE: To reduce chip size by providing a second conductivity type extended drain area which contacts with a drain contact area, providing a first conductivity type area which is biased reversely to the extended drain area in the extended drain area and permitting the surface of a semiconductor substrate between the extended drain area and a source area to be a channel area so as to provide a gate electrode on the channel area through a gate oxide film. CONSTITUTION: Boron is ion-implanted in an extended drain area 11, some heat processing is performed, then, the surface of a semiconductor substrate 15 is thermally oxidized. Thus, the segregation coefficients of the boron in a silicon oxide film 8 and the boron in silicon are differentiated. Thus, the boron density at the surface of the substrate 15 is reduced to be N-type and a P-type area is buried in the extended drain area 11. The P-type area 10 is biased reversely to the drain area 11 and depletion layers are spread between the extended drain area 11 and the semiconductor substrate 15 and between the P-type area 10 in the extended drain area 11 and the extended drain area 11. Therefore, the on-resistance between the drain sources becomes smaller than the MOSFET of the conventional structure. COPYRIGHT: (C)1992,JPO&Japio

Method for producing smooth surfaces on plastics

Abstract: Plastic objects are exposed to a gas mixture containing fluorine and a gaseous oxidizing agent, to produce an extremely smooth surface on the objects. The oxidizing agent can be oxygen, and the object is preferably exposed to the gaseous mixture for about 10-30 seconds. The surface of the object treated according to the present invention is found to be considerably more smooth and glossy than objects treated with fluorine alone, without the oxidizing agent. The surface formed according to the present invention therefore minimizes the contact area between the treated object and the surrounding media.

Method of forming a microelectronic contact

Abstract: A method of forming an integrated-circuit device (10) which provides increased packing of unrelated conductors such as first gate (14) and second gate (16). Strap (20) electrically connects conductor contact area (28) to moat contact area (30) and yet also overlies and overlaps gate (16) above the overlap area (27) without any danger of shorting first gate (14) to second gate (16). According to the invention, the possibility of shorting strap (20) to second gate (16) and hence first gate (14) to second gate (16), is eliminated in the processing sequence wherein second insulating layer (24) is patterned to expose conductor contact area (28) at a prior step in the processing sequence. Subsequently, a third insulating layer (26) is formed to re-cover conductor contact area (28), yet the thickness of third insulating layer (26) is substantially less than the combination of the thickness of third insulating layer (26) and second insulating layer (24). Hence the etching requirements to re-expose conductor contact area (28), when moat contact area (30) is also exposed, is diminished. Hence the etch to expose conductor contact area (28) and moat contact area (30) does not run the risk of exposing gate (16) at overlap area (27), since the insulation over overlap area (27) is substantially thicker than third insulating layer (26) as noted above. According to the invention, strap (20) is formed to overlie second gate (16) so that second gate (16) may be laterally disposed immediately adjacent moat contact area (30).

Tool Life in Oblique Cutting as a Function of Computed Flank Contact Temperature

Abstract: The steps by which a tool life analysis applicable to orthogonal cutting can be extended to accommodate tool obliquity are detailed. By following these, a relation between tool-life, T , tool obliquity, λ , and a representative tool flank wear land contact temperature, θ fs , is obtained. A method is then described by which θ fs in oblique cutting can be computed. This is based on a recently developed procedure for estimating temperatures of obliquely moving heat sources on the rake face combined with the influence of constriction resistance occurring at the discrete contact points within the flank contact area. In this way, from a knowledge of the T − θ fs relation applicable to a given tool/workpiece combination cut orthogonally, tool lives at different tool obliquities are predicted and are shown to agree quite well with experimentally determined values. Finally, a comprehensive tool life expression independent of cutting parameters and of tool geometry is proposed and is verified using data obtained by cutting mild steel with H.S.S. tools.

Device for coating web material

Abstract: In a coating device, a doctor blade is bent S-shaped for application of its contact force by means of a pressure bar. An additional force of a profile correction device is exerted for profile correction by means of magnets. This additional force acts preferably opposite to the main contact force. This prevents the profile correction device from causing a change of the geometry of the doctor blade in the contact area of the spreading edge of the doctor blade.

Super self-aligned technology for backside contact solar cells. A route to low cost and high efficiency

Abstract: A new technology is proposed for backside contact (BSC) silicon solar cells. This technology is self-aligned since only one photolithography step, without alignment, is required instead of the four to six steps required in previous technologies. Compared to a recently reported self-aligned process for BSC cells, this one eliminates the problem of compensated regions and has the advantages of a reduction of the emitter area, a passivation of silicon surface with thermal oxide between metal fingers, and a reduction in the metal-silicon contact area. As a consequence, this self-aligned technology offers great potential for the fabrication of high-efficiency solar cells at a low cost. >

Apparatus for tapping a fluid through a wall

Abstract: An apparatus for tapping a fluid through a wall, comprising a vacuum source (24), a tapping head (1) provided at the front thereof with a circumferential seal (3) bounding a contact area, perforating means (4) to be brought into a position extending through the contact area, and at least one conduit (11, 111, and 211) communicating with the contact area for discharging air from the contact area enclosed by the seal (3) and for discharging fluid released. The invention provides an apparatus for easily and reliably tapping fluid that may be under excess pressure through a wall. In the contact area a reduced pressure can be generated by the vacuum source, resulting in that the tapping head is held against the wall and moreover no fluid can release into the atmosphere.